Update django/python versions on tox.ini

tox.ini

@@ -1,30 +1,30 @@
 [tox]
-envlist =
-    py36-{flake8},
-    {py36,py37,py38,py39}-django32,
-    {py38,py39,py310,py311}-django{40,41,main},
+envlist = {linux}-py{38,39,310,311}-django{32,40,41,42}
 
 [gh-actions]
 python =
-    3.6: py36
-    3.7: py37
     3.8: py38
     3.9: py39
     3.10: py310
     3.11: py311
 
+
+[gh-actions:env]
+OS =
+    ubuntu-latest: linux
+DJANGO =
+    3.2: django32
+    4.0: django40
+    4.1: django41
+    4.2: django42
+
 [testenv]
 commands=
     py.test --cov=templated_email tests/
 deps=
     -rtox-requirements.txt
     pytest-cov
-    django32: Django==3.2
-    django40: Django>=4.0,<4.1
-    django41: Django>=4.1,<4.2
-    djangomain: https://github.com/django/django/archive/main.tar.gz
-
-[testenv:py36-flake8]
-commands = flake8 templated_email tests --ignore=E501
-deps =
-    flake8
+    django32: django~=3.2
+    django40: django~=4.0
+    django41: django~=4.1
+    django42: django~=4.2